Drop-In Anchor

How a drop-in anchor works

A drop-in anchor is an internally threaded steel sleeve with an expansion cone inside. You drill a hole, drop the anchor in flush with the concrete surface and drive the cone down with a setting tool and hammer. That expands the bottom of the sleeve against the hole, and friction holds it. What is left is a flush, female thread for a bolt or threaded rod, which you can remove and refit.

Hobson lists them for handrail fastening, formwork support, mechanical, electrical and pipe brackets, and hanger systems for pipes, cable trays, ducts, ceiling frames and ceiling fans. The everyday job is hanging threaded rod from a concrete ceiling for pipes, ducts and cable tray. Hobson's AS 5216 compliance note explains that an anchor used to AS 5216 must be assessed with a European Technical Assessment (ETA), and lists Drop-In PRO among its anchors with one. So overhead services and any structural or safety-critical fixing need an ETA-assessed anchor such as Drop-In PRO, with the type, size and spacing from the engineer's or services designer's specification. The standard zinc yellow and 316 drop-ins have no ETA and their data sheet values are for non-cracked concrete only, so they are not for overhead or safety-critical fixings.

Drop-In PRO, standard or Mungo drop-in?

• •Drop-In PRO (Conxtruct, zinc plated, plain or lipped): European Technical Assessments ETA-19/0673 (Option 7, non-cracked concrete) and ETA-19/0703 (ETAG 001 Part 6, multiple use in non-structural applications in cracked and non-cracked concrete, with fire resistance values). Hobson labels M8 and larger as fire rated; M6 has no fire resistance values. Hobson's AS 5216 compliance note lists Drop-In PRO among its anchors with a current ETA.
• •Standard drop-in (zinc yellow M6 to M20, 316 stainless M6 to M16) and the lipped M10 x 30 bucket: no ETA. Hobson's data sheets give installation values and working loads in 32 MPa non-cracked concrete only, for light to medium duty fixings. They are not for overhead services or safety-critical fixings, which need an ETA-assessed anchor.
• •Mungo MEA (zinc plated) and MEAR (316): ETA Option 7 and Part 6 on most sizes, as shown in the table, with fire resistance up to F120 part of the approval according to Mungo's sheet. M12 x 50: design it to Part 6 (ETA-18/0269), which uses the 15mm drill; we give Part 6 values only for this size. MUMMEAE01741250 is the 15mm drill version. MUMMEAE01741251 is a 16mm drill version, which the Part 6 approval does not cover (its M12 drill is 15mm), so we give no approval values for it. MEAR is 316 stainless (A4-50); Mungo's sheet refers to its approval, which is not among our documents, so check it covers your conditions.
• •Mungo ESA and ESA-R: drop-in anchors with no data sheet among Hobson's documents for this range, so no installation values are given here. Ask us before you specify them.
• •Lipped or plain: a lipped drop-in has a lip at the top that sits on the concrete surface; a plain drop-in has none. Drop-In PRO comes both ways (M16 lipped only); the standard lipped drop-in comes in the M10 x 30 bucket.

Drop-in anchor sizes

A drop-in anchor is sized by its internal thread: an M10 drop-in takes an M10 bolt or rod, but needs a bigger hole (12mm). Length is the anchor length, which is also its embedment.

How to install a drop-in anchor

1. Drill the hole at the drill size for the anchor (an M10 drop-in takes a 12mm hole) to the hole depth for that range, using hammer drilling.
2. Clean the hole: blow the dust out.
3. Drop the anchor in until it sits flush with the concrete surface.
4. Set it: put the setting tool for that range and size into the anchor and hammer it until the tool seats. Hobson's setting tools give a visual check that the anchor is set.
5. Fit the fixture and the bolt or rod. Hobson recommends a torque wrench: do not go over the installation torque for the range, and keep the bolt's thread engagement within the figures below.
6. Keep to the minimum edge distance, spacing and concrete thickness for that range. They are part of the conditions behind every published value.

Which setting tool?

Each range has its own setting tool, sized to the anchor, and the tool is what tells you the cone has been driven far enough. Use the tool made for the range and size you are setting.

Drop-In PRO installation values (ETA-19/0673 and ETA-19/0703)

Both Drop-In PRO ETAs give the same installation table. Conditions: hammer drilling; a bolt or rod of property class 4.6, 5.6, 5.8, 6.8 or 8.8 to ISO 898-1; bolt length = fixture thickness plus the thread engagement shown; dry internal conditions. Option 7 (ETA-19/0673) covers non-cracked concrete C20/25 to C50/60. Part 6 (ETA-19/0703) covers multiple use in non-structural applications in cracked or non-cracked concrete C12/15 to C50/60, where the slip or failure of one anchor will not significantly affect the fixture. Both ETAs say the anchorage is designed by an engineer experienced in anchorages and concrete.

Standard drop-in installation values and working loads

For the standard zinc yellow and 316 drop-ins and the lipped M10 x 30 (no ETA), from Hobson's three drop-in data sheets. The 316 sheet (M6 to M16) and the lipped sheet give the same values as the zinc yellow sheet for the sizes they share. Do not use these values for Drop-In PRO or Mungo codes.

The working load in tension is Hobson's figure for 32 MPa non-cracked concrete at the embedment shown, with a factor of safety of 3.0 on concrete and 2.5 on steel already included. It applies only at or above the minimum concrete thickness, edge distance and spacing in the table; the sheets give no reduction for anchors nearer an edge, closer together or in groups, so those need a design by an engineer. The bolt or rod you fit must be rated for the load too. These values are for non-cracked concrete only: overhead services and structural or safety-critical fixings need an ETA-assessed anchor such as Drop-In PRO, designed by an engineer.

Mungo MEA and MEAR spacing, edge distance and thickness

From Mungo's MEA drop-in anchor sheet and Table B1 of the two MEA ETAs, which give separate minimums for the ETAG 001 Part 6 approval (ETA-18/0269: multiple use, non-structural, cracked and non-cracked concrete) and the Option 7 approval (ETA-18/0236: non-cracked concrete). Use the pair for the approval your design relies on; n/a means that size is not covered by that approval, or (M12 x 50) that we give its Part 6 values only. Mungo's design software and the ETAs give the rest of the design data. Part 6 values for M10 x 40 and M16 x 65 are from ETA-18/0269 Table B1; Mungo's sheet omits these sizes.

M12 x 50: design it to Part 6 (ETA-18/0269), which uses the 15mm drill; we give Part 6 values only for this size. MUMMEAE01741250 is the 15mm drill version. MUMMEAE01741251 is a 16mm drill version, which the Part 6 approval does not cover (its M12 drill is 15mm), so we give no approval values for it.

Which finish for where?

• •Zinc plated (Drop-In PRO, Mungo MEA and ESA) and zinc yellow (standard drop-ins): low corrosion resistance on Hobson's finish comparison, for dry indoor or enclosed fixings. Both Drop-In PRO ETAs are for dry internal conditions only.
• •316 stainless (standard 316 and ESA-R): for damp, exposed and coastal fixings. MEAR is 316 stainless (A4-50); Mungo's sheet refers to its approval, which is not among our documents, so check it covers your conditions. Hobson's corrosion guide calls for stainless in the sea spray zone and within 2m of a pool. 316 is not made to sit in seawater.
• •Use a bolt or rod with the same corrosion protection as the anchor.

Drop-in anchor, concrete screw or chemical anchor?

• •Drop-in anchor: a flush, removable thread in solid concrete, at a shallow embedment. Set with a setting tool; load once correctly set.
• •Concrete screw: a screw-in anchor that can be removed. Its base materials, edge and spacing distances are on the concrete screw page.
• •Wedge anchor or through bolt: a stud anchor fixed through the fixture, where a protruding stud is fine.
• •Chemical anchor with an internal thread anchor: a flush thread set in resin, with no expansion forces on the concrete, for closer edge distances. See the chemical anchor bolts page.

Drop-in anchors in Adelaide

Allmat supplies Drop-In PRO and standard drop-in anchors, setting tools, threaded rod and drill bits to electricians, plumbers, HVAC and fire services contractors, ceiling fixers and builders across Adelaide and South Australia. Add them to a quote with the rod, nuts and washers for the job, and we will price the lot.

Questions